Face texture in Maya

by Ryan Bird

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Texturing is the process of adding detail (color, bump, specular, and so on) to a 3D mesh. You typically add texture using 2D painting software, such as Adobe* Photoshop* or Corel* Painter*. Figure 1 shows two versions of the same model. The image on the left is an untextured mesh, while the image on the right is a textured mesh.

Figure 1. The untextured and textured versions of the fairy model

Does Size Matter?

Depending on the media a model is used for, the size of the texture does matter. Texture maps for video games and real-time environments tend to be smaller in size and have limits determined by the engine they are being made for. In contrast, texture maps for pre-rendered sequences (film and broadcast) can be much bigger. Generally, the sizes of these texture maps are only limited by what the rendering computer can handle. Regardless of the size of a texture map's target, it's important that those maps look their best. For this article, I create a 512 × 512, game-friendly map for my low-resolution fairy model.

UV Snapshot

Before I begin painting the texture, I take a snapshot of the UVs (that is, the mesh's U and V coordinates). I do this so that I have a guide for what I'm painting and know where everything needs to go.

Maya* provides a way to obtain a UV screenshot without having to use the Print Screen option on the keyboard: I select the mesh objects included in the texture map, then, in the UV Texture Editor, click Polygons > UV Snapshot.

The UV Snapshot window opens showing several options for saving an image for the UVs selected. Under File Name, I chose a location for the saved snapshot image and provide a file name. The Size X and Size Y fields define how big the snapshot image needs to be. at my texture map size would be 512 × 512 pixels, but that is not the size I enter. When I create texture maps for games, I always double the size of the map in case there is reason to have a higher-resolution map later (box cover renderings, cinematics, or even for portfolio purposes). So, I set my coordinates to 1024 × 1024.

By default, the Image Format is set to Maya IFF. Although Photoshop* reads this format just fine, I prefer to use the TIFF format for the UV snapshot, because the file size is much smaller and the quality is the same. I click OK to save an image of my UV snapshot to my designated folder.

Bringing the Snapshot into Photoshop
I now go into Photoshop*. When I open the saved UV snapshot image from my designated folder, it looks similar to Figure 2.

Figure 2. The UV snapshot image in Photoshop*

From here, I need to do a bit of preparation work on this image before it's ready to be painted. First, I get rid of the image's alpha channel. During the UV snapshot export process, Maya* includes an alpha channel with most file formats. If this alpha channel remains in the final texture and is saved as a TGA or TIFF image, the channel makes the mesh transparent when the texture applied to the mesh's material, showing only a textured wireframe. That's not to say that a custom alpha channel can't be added later; it's just good practice to get rid of the initial one.